Weather forecasting for paddlers
In the pub last night, I was asked how to find out what rivers are running and how to work out where to go. My method isn't fool proof, but it seems to work for me and can be improved with time and experience.
There are two different types of trips - those that need booking up in advance and those that can be organised on the spur of the moment. Most trips run by a club, trips abroad and larger trips will need booking up in advance in order to allow time to make transport and accommodation arrangements. Weather can't be booked in advance, but there are sometimes predictable weather patterns. In the Alps, for example, it gets warm in the summer and this means the snow melts causing the rivers to flow. The later in the summer, typically the lower the levels because some snow has already flowed out to sea. As another example, in the Fort William area of Scotland it's generally wet and between say, October and May, it's sufficiently wet that I've not had a problem finding rivers to run.
Those predictable weather patterns can be found in guidebooks for the area. In this country, booking a trip in advance is usually a case of being optimistic about the weather, praying lots or both. On the plus side, I'm struggling to recall a trip that I've been on that has failed to find something to run. Weather forecasts and river level predictions can be used to choose which rivers to head to once the trip has begun.
More detailed general predictions can be found on Metcheck for specific weeks throughout the year: http://www.metcheck.com/V40/UK/FREE/singularities.asp - but these are best guesses and I've yet to use them for trip planning.
Spur of the moment trips are arranged based on believing that there is water in a certain area and then driving for hours based on that hunch. To develop that hunch I typically look at 3 things: What has been happening, what is going to happen between now and me arriving and how will the rivers respond to that.
What has been happening?
- This needs to cover the last few weeks.
- Keeping an eye on the weather regularly is a good thing - watching the weather forecast daily, or popping along to http://www.bbc.co.uk/weather or http://www.metcheck.com/ every few days will give you a good idea of what is happening. I really like Metcheck, on the front page it gives you more in depth information about why the weather is like it is, which helps in the long run of understanding the weather. The Weather page on RUCC's website: http://www.rucc.co.uk/info/weather contains Metcheck's 5 day forecasts for North and South Wales as well as Dartmoor, so is good for a glance at what's happening.
- Observing what is happening in your home town will help too - generally if Reading is wet and the Thames is high, there will have been rain elsewhere too.
- Specific observations of recent conditions (the last 24hours normally) can be found from independent weather stations. Lots have online links to real time information, such as rain gauges. A list of thses can be found here: http://www.weatherstations.co.uk/aws_map.htm - these are very useful for finding out how much rain has fallen recently.
- Online gauges. When I was helping James F with the Thames Weir Project, he introduced a feature where by certain people can update a web page by sending a text message with information. This continues to be the best place to find out what the Thames Weirs are doing, although it is now hosted on Kayako Jacko's site: http://www.kayakojacko.com/community/weir/weir.php - these are typically updated as frequently as is necessary. In Scotland they're lucky enough to have a website that gives them (and us) updates on river levels: http://www.sepa.org.uk/data/river_levels/data.htm - this is updated daily.
- Telephone gauges. I must admit that I don't use these despite them being our only access to real time level updates from rivers around England and Wales, I think that's because I don't know how to turn the level numbers into a yes or a no for a given river. The individual river guides at http://www.ukriversguidebook.co.uk/rivers/ tend to contain a phone number if there is an telephone gauge available. There used to be a useful page on the RUCC website listing these, but it got a bit out of date and was removed. One telephone guide I do use it the Tryweryn Release line - useful info if you're heading to North Wales: 01678 520826
- Reading reports other paddlers have posted. http://www.ukriversguidebook.co.uk/forums/ is a good place to check. Some people like bragging about their paddling (meaning you can find out what has been running), others like asking about water levels (meaning you can find out what other people are thinking and can read the answers). Typically a lot of posts about lots kit means that river levels have been high.
- First hand information: If you know anyone who lives in a paddling area, ask them about the river levels or weather. Even if they're not a paddler they may know what a local river is doing. If you know paddlers who live in the areas we frequent, even better.
What is going to happen?
- Weather forecasts. By following the weather closely, reading the reports on Metcheck's homepage and seeing a recent weather forecast you can generally predict what's going to happen. Metcheck's 5 day forecast is pretty good - it tells you in mm how much rain is expected. All you really need to know, however, is: "is it going to rain?" (although knowing if it'll freeze is useful too, since frozen water doesn't help river levels).
- Checking the forecasts. Once you're in the area it can be hard to get online to check weather forecasts, so I sometimes put a saucepan outside the bunkhouse so that I can see how much it rains overnight.
How is that going to affect the rivers?
Now that you know what has happened and have a guess at what will happen, you need to put that together and work out what the rivers will do as a result. There are lots of people who make livings out of measuring, predicting, modeling and changing how rivers are affected by the rain, unfortunately for you - I'm not one of them. The knowledge I have is a poor substitute for actual understanding, but it helps a little in guessing what rivers are going to be running. There are some things you need to know: how fast the river run off is and how much water a river needs to make it worth paddling.
The run off is how long it takes the rain to run off the hillside and into the river, this dictates how soon after rain the river is runnable and how long it stays runnable for. Generally the higher up the mountain you are, the faster the river will rise. If the river is fed from moorland (like the Dart) it will often hold water for longer, meaning that it can be paddled a longer time after rain than other rivers. On managed rivers (those with dams) all bets are off and you'll need to find out if the dam is releasing enough to make it worth paddling. Local sources help with this.
Finding out how much water a river requires is tricky and often the subject of disputes. Generally speaking, the lower down the mountain a river is, the larger it's catchment which means that more of the rain is collected and funneled into the river. The nature of the river makes a huge difference, though. Gorge runs, where the river is squeezed between two rock cliffs tend to be deeper and require less water to make them paddleable than open sided rivers. Local knowledge and guidebooks help. Once you're on the ground you can use guidebooks, along side your own experience to make guesses related to observations. E.g. you can read that river A takes X amount of water to run, but if it's slightly too low, you need to look at river B which the guidebook says takes less water. Guidebooks often point to locations where gauges are on rivers, these maybe bits of wood with numbers on them or something less quantitative like saying that if you can float at the put in the rest will be fine.
Bringing it all together
The question you're looking to answer before you arrive at the river is: Which rivers might be running. This is all just guess work and isn't any substitute to getting up early and allowing yourself enough time to drive around between rivers looking for one that is running.
Something that I've found is well worth thinking about during the planning stages of a trip is low water options. If the worst happens and there is no rain, or the rivers are lower than expected, what are you going to do - where can you go and still paddle? These options tend to be rivers further down the catchment area (like the Dee or Rondda), dam controlled rivers (Tryweryn, Tummel) or rivers that are runnable in almost any level (e.g. Spean Gorge, Etive, Dee). High water options generally involve running something easier than you normally would (e.g. if the Dart loop is too high, then the Lower Dart might be suitable for your group.
I've found that it is well worth making notes in a guidebook (use pencil or post-it notes if you like) to help your memory next time you're in that area.
I hope that makes the situation a little clearer. Any questions, comments, suggestions or corrections can be sent to david@cognite.net.
David Webster - February 2007.